Poking holes in the Gravity trailer with NASA’s help

We sit down with the guy who trains spacewalkers to see what's right—and wrong.

I haven't seen Alfonso Cuarón's Gravity yet, but I want to. The movie will enter general release here in the US on October 4. It stars George Clooney and Sandra Bullock as two astronauts having what looks to be a really, really bad day in space. Trailers for the movie show them flying around in their space suits, yelling and crying and dodging debris from exploding satellites and space ships and space stations, all lit by a beautifully rendered and untouchably distant Earth in the background.

The director and the studio have taken great pains to recreate the experience of operating in microgravity as accurately as possible. Cuarón consulted with NASA astronauts on the particulars of moving in microgravity, and, according to the NY Daily News, the movie's production designers studied thousands of NASA photographs in order to make their vision of space look authentic.

When asked how far that commitment to verisimilitude stretched, though, Cuarón said that while the movie strives for accuracy, "it would be disingenuous to say we did it 100 percent, because this is a movie, and we needed to take certain liberties."

The five minute-plus extended trailer for Gravity. Keep this video handy, because we're going to give it the MST3k treatment in just a moment.

There was a five-minute "extended trailer" for the movie published last month. It certainly had some gripping visuals, but the longer it went on, the deeper my frown became. I don't claim to be an expert, but the stuff that George Clooney and Sandra Bullock were doing on the screen just didn't look right. Certainly cool, but not right.

But this is Ars, and on certain things, we have the hook up. I may not be the expert, but I knew someone who was, and I was going to ask for his official opinion on that extended trailer.

The man who makes the plan

The last time I talked with Zeb Scoville was at NASA's Neutral Buoyancy Lab, the enormous indoor pool where NASA trains its astronauts on how to spacewalk—or, more properly, how to function during extravehicular activity, or EVA. Scoville is the EVA task group lead at the NBL, and he is responsible for managing the teams that figure out how EVAs work. If an EVA's goal is to replace a part outside the space station, for example, Scoville figures out exactly what the astronauts need to do to replace the part, including the physical movements they need to make. His team is made up of actual NASA flight controllers—during training at the pool, they run the simulations, and during the actual missions, they're manning the consoles in Mission Control.

Enlarge/ NASA EVA Task Group manager Zeb Scoville, standing in one of the test coordinator control rooms at the Neutral Buoyancy Laboratory. Visible behind him is the NBL pool.

Steven Michael

If anyone could shed some light on the accuracy or inaccuracy of Clooney and Bullock's space antics, I figured Scoville would be the man. After a quick call to NASA's press office to arrange some time to talk, we sat down together to watch our way through the trailer.

Problem: debris

The trailer kicks off with an EVA in progress, and a radio-distorted voice is heard calling for an abort. It becomes clear that the message is directed at some astronauts working on something outside their spacecraft. It looks like they're repairing the Hubble Space Telescope, though it might be something else—for instance, some KEYHOLE reconnaissance satellites are said to share the Hubble's external form factor. Whatever it is, the astronauts are outside with big debris incoming, which means they're in trouble.

Enlarge/ Screencap from the trailer, showing the start of a giant debris storm. Note the monstrous size of the piece of debris near frame center.

Warner Bros

Right away, the sheer size of the debris gave us pause. NASA relies on US Strategic Command's big radars to keep constant radar watch on its vehicles, and the chunks shown on-screen are far larger than the minimum size that USSTRATCOM would notice. "Part of the procedure for getting ready for an EVA would include checking for debris like this, wouldn't it?" I asked.

"Right—we have a process that's known as a 'certification of EVA readiness,'" answered Scoville. "We have the EVA community come together, and they'll present a lot of the technical analysis, and we give our community-wide consensus for a 'go' for the EVA." Scoville explained that this analysis includes an assessment of the risk of encountering orbital debris during the EVA. Space isn't empty, especially at the International Space Station's low altitude, and there's always the chance that there'll be a "conjunction," NASA-speak for a potential collision between debris and a vehicle or astronaut. Debris risk is assessed in terms of the potential damage—whether the expected amount of debris could cause a suit leak small enough to survive (which would terminate the mission), or whether it could cause loss of a spacecraft or even astronaut lives.

"The debris they have there is orders of magnitude larger than what you need to create a very catastrophic puncture in a space suit. For comparison, if you have up to about an eighth inch of a hole in an EMU"—that's Extravehicular Mobility Unit, NASA's acronym for a spacesuit—"it has emergency oxygen systems which can feed that leak and maintain pressure for about 30 minutes to get you back inside the airlock and repress the airlock. Above about an eighth of an inch, and it can't maintain pressure."

"Is there a procedure for what to do if that happens?" I asked. "Like, you stick your finger in the hole or try to squeeze the leak closed?"

Scoville responded in the negative because of the spacesuit's many-layered structure. "On the inside, you have the bladder layer, that actually maintains the pressure of the suit. Beyond that there's the restraint layer, and then you have a neoprene layer, and beyond that the insulation mylar layers for heat rejection, with layers of scrim in between for separation, then the white Ortho-Fabric on the outside. No matter how much you squeeze or push on the outer layer, you're not getting to the inner layer where the bladder is. You wouldn't be able to seal that with a gloved hand with 4.3 pounds of pressure trying to get out of the suit."

Although an EVA wouldn't be allowed to happen under such conditions, Scoville speaks up here and lets me know that he's actually Googled a plot summary of the movie in preparation for our talk. The debris in Gravity actually comes from an event that occurs after the EVA has started. Under such circumstances, the EVA would indeed be terminated, just as is depicted in the trailer. I stow my nerd rage, and we continue.

Problem: Clooney's jetpack

After the debris zips past, intrepid astronaut George "The Chin" Clooney comes in frame, sporting a very cool space jetpack. There's a problem with that backpack, though—nothing like it exists in NASA's active inventory anymore. To me, it looks like Clooney's character is supposed to be wearing a Manned Maneuvering Unit or MMU, a piece of equipment developed for shuttle astronauts to use while repairing satellites. The MMUs worked great, but they weren't used very much, and NASA discontinued flying them in the 1990s. They weren't re-introduced for use on the International Space Station because they're too large and bulky.

I point this out to Scoville. "Yeah," he replied. "It looks not quite like a MMU, but it's something close to it. Those things, the manned maneuvering units, are no longer used. In some of those shots, it looks like a cross between a MMU and a thing we call SAFER, which stands for 'Simplified Aid for EVA Rescue,' which is similar to a MMU—except it doesn't have the same level of redundancy, it's not as large, the joystick is a little different, and it doesn't hold as much gas."

The SAFER backpacks are for astronauts working around the International Space Station, and as the acronym suggests, they're intended to be used in case an astronaut accidentally drifts away from the station. Scoville explains that the little safety jetpack has 24 thrusters powered by the venting of compressed nitrogen gas, and it can accelerate an astronaut up to about 10 feet per second. The SAFER also has a smart gyro-based stabilization system that will automatically stop an astronaut from tumbling. However, these packs aren't intended to be used as the primary means for flitting about outside. The limited amount of delta-v the backpacks can impart is more than enough to stop a drifting astronaut, but the amount of propellant is very limited.

SAFER backpacks weren't used on shuttle missions, either: "On shuttle missions, when they weren't docked to station, they didn't need this—they could just fly the shuttle after them to pick them up if they fell off." This provides one explanation for why Clooney's character is wearing a jetpack and Bullock's character isn't—when we meet her in a moment, she's strapped into the foot restraints at the end of the space shuttle's remote manipulator arm, busily working away at repairing the telescope.

Lee Hutchinson
Lee is the Senior Technology Editor at Ars and oversees gadget, automotive, IT, and culture content. He also knows stuff about enterprise storage, security, and manned space flight. Lee is based in Houston, TX. Emaillee.hutchinson@arstechnica.com

166 Reader Comments

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

just a vehicle for us to learn more about space. at least i found it interesting.

imitating physics with 100% accuracy is not this movie's job and can't be slighted for it.

That's what I was asking. How long does it take? I know the debris was created after the EVA, just curious how long it would to take to relay that information and abort.

Ordinarily, I could make a quick phone call and get a near-instant answer, but all of NASA's public affairs office is shut down right now. So, I don't know.

Based on my interview with ISS TOPO controller Josh Parris, I'd guess the answer is pretty damn quickly. When an EVA is active, everything at the NASA centers is at a high state of readiness; plus, potential impingements into the the 50x50x4km "pizza box" around the ISS are continually monitored by ground-based radar. The maximum amount of time it would take for a new breakup event to be noticed would be the orbital period of the debris, and potentially much sooner.

The Congressional Inquiry could be good! The Majestic pretty much climaxes with Carrey's character in front of the HUAC. There are also plenty of courtroom dramas out there.

Or maybe I'm just weird. I read Clancy's The Bear And The Dragon a couple of years ago (oh, what a piercing of teenage fandom!) and the first 600 pages were awful ideological indoctrination (and I'm on his side!), but I found Clancy's description of the logistics of the Sino-Russian war was terrific and more exciting than the fighting.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

For me, it's the science teacher in me that goes nuts. Try as we might, it's really, really hard to get kids mind from the huge, dramatic Hollywood version of science to the often much more sedate form of real science. That's not to say that there isn't cool stuff in real science, it's just not as dramatic (go figure) as the movies.

You have no idea how many times I've had to debunk Armageddon, 2012, The Day After Tomorrow, The Core, Volcano, Dante's Peak, and just about every other disaster movie known to man. (Brosnan outrunning a pyroclastic cloud in a pickup with no tires? Yeah, not gonna happen. We would end up with crispy Brosnan long before the cool busted arm moment.)

Debunk them? That's where you're messing up. Just encourage the kids to figure out how to make them work.

Or, to put it even more succinctly—in old western movies, no one ever shoots the horses out from under the charging mob of bandits to quickly end the fight and save the day. Why? Because if they shot the horses, there'd be no movie.

Mal: Remember, shoot the man, not the horse. Dead horse is cover; live horse great pile of panic.

That's what I was asking. How long does it take? I know the debris was created after the EVA, just curious how long it would to take to relay that information and abort.

Ordinarily, I could make a quick phone call and get a near-instant answer, but all of NASA's public affairs office is shut down right now. So, I don't know.

Based on my interview with ISS TOPO controller Josh Parris, I'd guess the answer is pretty damn quickly. When an EVA is active, everything at the NASA centers is at a high state of readiness; plus, potential impingements into the the 50x50x4km "pizza box" around the ISS are continually monitored by ground-based radar. The maximum amount of time it would take for a new breakup event to be noticed would be the orbital period of the debris, and potentially much sooner.

I re-read the TOPO article and saw the 28.5 hour maneuvering plan. I guess the PDAM should cover unexpected debris.

Ok, so USSTRATCOM tracks what's up there. What would the reaction time be if there is new debris created due to a meteor shower? How long to calculate the trajectory?

Did you read the whole article? Scoville said the story had the debris created after EVA initiation and so was a legitimate plot device.

That's what I was asking. How long does it take? I know the debris was created after the EVA, just curious how long it would to take to relay that information and abort.

If I remember correctly there is a zone ~750m (above/below) and ~25km around that needs to be clear. (edit to add this comment)

The safety zone around the ISS is 1.5 x 50 x 50 kilometers and is shaped like a pizza box. However, scheduling a Debris Avoidance Manoeuvre (DAM) takes about 30 hours and has been done about 11 times. Generally a collision warning for small debris is on the order of minutes. About a month after the Iridium satellite collision, a stray chunk of motor was detected on course with the ISS. An alert was sent to the crew to climb into the Soyuz capsule and prepare for possible collision. They only had a few minutes until it passed by within a mile. Had an EVA been taking place during this time, there probably would not have been enough time to abort.

This would be a cascade of collisions with the majority of debris being small bits. Large chunks of debris (such as the one in the trailer) would probably be much easier to track and less likely to move drastically off a known trajectory. Personally I think it would have been much more terrifying to be hit by thousands of micrometeorites you can't see coming... but it's not as suspenseful as seeing the ISS ripped apart.

There's a stretch between "not as it is done in reality" , "not rational but physically possible" and "physically impossible".

A fiction can be not 100% accurate and still retain some plausibility. That said, this movie seems to touch only the second category, which is not that bad.

Not sure I understand your point. You think a film portraying people acting irrationally is a problem?

Not necessarily, but if it's Prometheus level irrational acting, yes, it's a problem.Usually, it decreases plausibility a bit, but increases the story a bit more, and I find it all well.At some point though, it stops helping in my opinion.

Just on the orbital dynamics, was it the actual Hubble Space Telescope they were servicing? If it was a fictional one or a spysat with an orbital plane closer to the ISS's, would that make it more believable? Or are all the Keyhole sats in HST-style orbits? (Maybe all the spysats are closer to polar orbit, which would give an even bigger orbital plane differential?!)

Whatever. For drama, no matter how realistic you make things, in the end, things have to move at the speed the plot requires and they are not subject to the normal laws of physics.

Finally, a question for the people who know: how do the suits communicate? Is it point to point, or do they need to relay through the shuttle/ISS?

This is what I was thinking. They are flying in a fictitious shuttle. So, it takes place is a parallel fiction universe to start with. At that point, it's not so much, "Is this an accurate depiction of the real universe," as it is "Is this a depiction of a plausible universe." If the movie specifies orbital parameters that are impossible to get between, then it sort of fails at realism. OTOH, if the movie is more vague then it is perfectly reasonable to conclude that, given they are able to travel between the two spots, they must be quite accessible to each other. Maybe in this universe, ISS was launched before Hubble to to funding decisions, so it was decided to specifically put Hubble in an orbit where a shuttle could go between them. Willful suspension of disbelief FTW.

Haven't studied the comms system in detail, though. Can't answer that. (Though I once know somebody who worked at Lockheed's manned spaceflight group doing comms. She would probably know.)

I only saw the short TV commercial trailers and while it looked stunning, I immediately had a bad feeling about accuracy and the casting of Sandra Bullock.

The plot reminded me of two other films. The EVA scene in the 2000 movie "Mission to Mars" which had an absolutely horrible EVA scene - at least science wise. The other movie was the 1969 film "Marooned" which, as I remember, the science was done pretty well for its time, however its been 35 or 40 years since I actually saw it and my opinion may be different now.

I'm actually interested in seeing the movie myself. I think about how these people go up, into the vacuum of space, and there really are an incredible amount of things that could go wrong. From the looks of the trailer, they just simply all do - at the same time.

Still, to have something like that happen would be terrifying. Just kinda float off into nowhere... Should be pretty entertaining IMHO and while I -do- enjoy realism (prime example of absolutely ZERO realism == Armageddon), I do want to be entertained as well and if they had to take a few liberties, so be it.

"Gravity 2: The Congressional Inquiry". Priceless and would probably watch it too.I don't know why but I greatly enjoy going over the Rogers and CAIB reports. There is something fascinating in understanding how and why complex systems fail. My next on the list to read is Fukushima NAIIC's report.

They're doing basically that next month with "The Challenger Disaster" on TV.

Its a movie, its suppose to be fantasy and entertainment. Its not suppose to be real. I don't see the need to analyze every little thing in a "NASA says this isn't correct" aspect. Sometimes its just nice to let your mind relax a little and enjoy the fantasy of a movie, not everything has to be correct all the time for that to happen.

The fact that Bullock flew off untethered into space and just kept going gets me. How could anyone possibly have caught up to her to rescue her from that? Seems like it should be a pretty short movie...

But since no one else has mentioned it, I'm guessing there is something I'm overlooking otherwise there would've been more posts about this?

There's an old saying about science fiction that people are prepared to suspend their disbelief for the impossible (Woohoo! Warp Drive!) but you lose them very quickly when you introduce the extremely improbable (Woohoo! I hacked into the NSA in 12 seconds while getting a blow job by guessing an analyst's cat's name!).

I suspect most of what will offend here is not the impossible (flying from the Hubble to the ISS) but rather the improbable (haven't seen the movie so I don't have an example, but no doubt there will be plenty of em).

I agree that the level of emotion in the astronaut's voices is higher than I hear during real emergencies in space (listen to the Apollo 13 recording some times).

Even accepting that the debris was caused recently; given the relative disparity in vector, how close would something have had to have been for that lack of warning?

Why not move the entire shuttle with astronauts attached? Given it's vulnerability (shown by its nigh-destruction), it seems the simplest and only effective response would have been to fire the maneuvering thrusters and get everyone (except perhaps Clooney) out of the way.

"Detach from the arm or it will carry you too far"? Her vector wouldn't change because she detached (unless she was "thrown" by the arm, if I assume she was not near the center of mass; but in that case without timing, her vector could get much worse rather than better).

Do the helmets fog like that under heavy breathing? I would think that would be avoided.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

I think it's incredibly precious to expect a non-documentary film on general release to the unwashed masses to represent one's field with 100% accuracy.

Name one film released this side of 2000 that was 100% accurate. Most of them are at about 20%, and scifi at about 1%. If a film hits even 80% it's done a spectacular job.

Repeat after me: fiction isn't fact.

Whoever said it should be? Some people (evidently not you) have an interest in science and would like to know how accurate this film is. It's curiosity and have driven scientists for centuries. If you don't care then just watch the movie and don't read the article.

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

Devil's Advocate: People get plenty of realism in real life, people play games and go to movies to get away. It needs to be close enough to real to tease the mind, but take liberties to be different, because different is exciting and new.

Strangely enough, what jumped out at me was the tether that broke. Run of the mill consumer climbing gear can withstand forces much, much greater than a couple heavily loaded people traveling at a handful of fps. You telling me NASA grade gear snaps like twigs?

Wait wait wait. I've never sat through the extended trailer and just watched it. Let me get this straight. They're on a shuttle, and the shuttle blows up. They somehow make it to the ISS, which then proceeds to ALSO blow up?!?

Why is everyone so quick to try to find this movies failures? It looks to be a really exciting, and thrilling movie. Why destroy it before people see it - not based on the quality of the movie itself, but the science. Last time I checked this was not a documentary...

probably for the same reasons that climate scientists were doing the same for 2012 and the day after tomorrow. When it's your field of interest then you "like" to see it shown accurately

Devil's Advocate: People get plenty of realism in real life, people play games and go to movies to get away. It needs to be close enough to real to tease the mind, but take liberties to be different, because different is exciting and new.

Devil's Advocate Advocate: I do crap in excel all day at work, I like to read about (real) space science in connection to a movie on my down time. Because I find much of the science of space more entertaining than made up stuff.

And why do half the people here assume that the existence of this article somehow advocate for changing all movies ever to comply with science? It's a fun analysis, you can still have your movie.